Method of producing ammonium sulfate.



F. TSCHUDY.

METHOD OF PRODUCING AMMONIUM SULFATE. APPLICATION FILED SEPT.2I. 1914.

1,155,385. Patented Oct. 5,1915.

Tana

METHOD OF PRODUCING AMMONIUIVI SULFATE.

Specification of Letters Patent.

Elli

Patented 5,

Application filed September 21, 1914. Serial No. 862,833.

To all whom it may} concern:

Be it known that I, FREDERICK TscHUDY, a citizen of the United States} and resident of l airfieldin the county of Jefferson and State of Alabama, have invented certain new and useful Improvements. in Methods of I roducing Ammonium Sulfate, of which the following is a specification;

This invention relates primarily to a method of purifying gases of carboniza-tion, and secondly. to a method of producing ammonium sulfate.

In the process of manufacture oil-ammonium sulfate (NI-IQ SO from. gases produced by distillation of fuel such as coal in col-:e ovens, gas retorts, and the like ,'the gas evolved from the fuel charged during the distilling period is usually cooled in order to condense the tar as Well as Water contained therein. The cleaned gases either previously superheated, or at the temperature they have attained when reaching the saturator are then passed through a bath. of sulfuric acid. In the saturatorthe ammonia is converted into sulfate while the gas is conveyed to the respective points of consumption. In such a process it is essential that the gas be cooled to a low temperature, at least to that nearest the dew point of tar, and considerably below the dew point of water. so that the gas leaving the coolers is free from heavy tar and practically. tree from tar oils and Water. The

Water present in the products of distillation originate either from the coal. as native moisture. or from the washed coal. as adhesive moisture. The process of water condensation starts in the gas conveying svstem where the temperature of the gas reaches the dew point of water and increases as the temperature of the fins drops toward the dew point oi the tar. The amount of condensation depends entirely on the physical condition of the coaL which when charged dry. usually gives oil during distillation from *l. to 5% of water. while in some cases where coal must be washed and charged comparatively wet. the total condensation of the water often amounts to over 16??- ot the we ght. of the coal charged. The water conilensl Q' out with the tar and tarrv oils in the system hetween the ovens and the saturators.v and the various interposed apparatus as well collH tin-" naiin fuel gas main. coolers. evhaustors. in! extractors. collected in urious inunn' and by diverse apparatus in -monia still to be evaporated.

containing a considerable amount oi tree and fixed ammonia is brought by diverse manners or various apparatus to the am- Evaporation of the ammonia, both free and fixed, from the liquor brought to the still is acco1nplished by well known application. of BL and "alkaline agents. The aqueous vapors containing the liberated ammonia are then either introduced into the before or after passing through the coolers, or they are taken directly into the sulfuric acid bath where the ammonia is separated by the bath and the aqueous vapors commingled with the oven gas. i

The oven gas, gradually giving oft heat in the mains through which it passes is cooled down in the cooler or condenser to the temperature as low as is consistent with the degree of tar extraction desired, usually to about 75 or 85 From the cooler the gas is taken up by the eXhausters and passed to the satn ator, either at the temperature it attains in the exhausters, or at a higher tem perature brought about by a reheating. Between the eXhauster and the saturator. a tar extractor of any design may be inserted it the condenser should not remove the tar to the desired minimum.

The process above described is followed with various modifications, but in all thereof it is evident that the gas is subject to an actual re-heating to a greater or loss extent even though stress is laid on the point that no gas is re-heated. Any gas. which by action of a machine, undergoes an increase in pressure. has its temperature increases ey the compression and the degree of heating depends entirelv on the amount of compression to which the gas is subiected. i Therefore wherever there is an exhauster placed between the cooler and the saturator. the gas convcved thereby is changed in tempt-1" uture and the cannot therefore reach in: saturato'r without a certain specific deal-cool rah-eating. The temperature rise in las passing: through the so-callcd blowers or exhausters rang-cs from 10 to.25 F. with rotary blowersdo from .20 lo 50 with low pressure ccutri'i'umil blowers-mud considerably ahoveflO? if the gas is subject'to a high compression.

The drawbacks in the several arranp nients mentioned are that they do not niit c an economical operation with the utilization of the least amountof energy F ji a in from some source other than the energy due to the heat of the gases; that they require large apparatus in which'the spacesare not acid bath.

"the capacit at a given water consumption but the "ater from the still and the water r mtamed m the gas, as previously alluded to, is condensed in the cooler, and a surplusihereof coming from the still acts as a diluter to the liquor derived from the aqueous vapor contained in the gas not condensed prior to reaching the cooler. This diluted liquor therefore has to be returned as weak liquor to the still to be again condensed. .In this manner the still is unnecessarily overloaded am the operation requires not only more steam but more water. By mixing the gas as alluded to, the suction side of the blower is loaded with additional weight required to convey the heavy aqueous vapors to the cooler.

Where the aqueous vapors of the still are mixed with the gases between the blower and thesaturator, they bring into the gas all the water their temperature is able to carry, and it therefore becomes necessary to keep the saturator bath at a temperature high enouglrto keep these vapors in suspension in the gas. If this be not done the condensed vapors would dilute the sulfuric In such operation the sulfuric acid bath must therefore be of a temperature approximately that of the mixed gas entering. This temperature is regulated in some of the processes by additional reheating of the gas while in other processes the vapors are super-heated to convey suliicient heat to the bath to maintain the high temperature required. In the case where the apors are introduced before the saturator, it becomes evident that the pressure of these vapors mtst be somewhat higher than the pressure of the gas leaving the exhauster. This requires that the still be operated under a pressure considerably higher than that required for 'iberating the ammonia. The pressure val we at the discharge end of the blower from a} to 5 pounds per square inch and the pressure at the still must therefore be sufficient to overcome the friction in the pipes conveyaig the vapors, as well as the pressure in the gas main where the vapors enter! In all cases where, to obviate the above described shortcomings, the ammonia vapors from the still are brought directly into the saturator bath, they must be intro duced at a pressure equal to that of the gas,

or a pressure even higher than that of the gas. This is accomplished either by high operative pressure on the still or then by bringing the vapors to the pressure required.

The object of my invention is to convey the gas from the coolers to the blowers at the lowest possible temperature. The blowers working at a minimum of compression, will increase the temperature. of the gas but slightly and I regulate the temperature of this gas inside of the saturator as well as the temperature of the acid bath by the use of waste heat of the aqueous vapors of the ammonia still, to a temperature about 40? F. less than the temperature which must be'mziintained by the several examples given above. A temperature of 100 to 105" F. is best adapted for an economical production of clean sulfate when the gases have been cooled to or below the dew point of tar, and

when they carry only the amount of water in suspension permitted by that temperature. This temperature, being lower than the temperature stated for the saturator bath, will permit keeping what little aqueous vapor that may be 1n the gas in suspension. At a temperature of from T0 to 85 F. tar and tarry oils have been removed, even without the use of the final tar extractor, to such a degree that no contamination of the sulfate need be feared. In this invention no other means for raising temperatures, such as steam, hot air, hot gas, or hot water are used, outside of waste heat inside of the saturator for the purpose of balancing the temperature of gas and acid bath. and heavy losses in pressure by Ire-heaters, or extra power used in boosters, or heating agents, used for raising temperatures of gas or vapors. are done away with. The temperatures stated relate to the use of sulfuric acid at degrees Be. If other than such acid is used, the temperature giver-i must be changed in accordance with the content of water in such acid as may be used.

The ammonia vapors are; liberated at the ammonia still under a low pressure just suf- 'ficient to overcome the friction in the pipe system. and the head of a small seal of acid in the'separator to which reference will be made later on. The ammonia still will operate in this manner under the minimum pressure and consumption of steam, and no appurtenances are used to accelerate the flow of the vapors or increase their pressure as originally attained in the still. Five pounds of steam pressure on the ammonia still, as against thirteen and fifteen pounds in common use will sutlice to produce the desired results.

' inventions. as there are several such sysaneaese My invention will be more readily understood by reference to the accompanying drawing in which the figure ii'afdiagrammatic illustration of a plant of the character described.

Referring more particularly to the drawing it Will be seen thatthe gases of carbonization coming" from the coke ovens 10, are collected in the gas collecting main 11, and reduced in temperature by radiation. Tarry matter is condensed in this main and flows through pipe line 12, into the foul gas main 13 as indicated. From the gas collecting main 11, the gases travel under suction of the enhauster 1%, to the cooler 15. By radiation, the temperature of the gas in the gas main 13, is reduced so that it gives 05 a tarry condensate containing part of the original moisture 'in the coal. This preliminary. or high temperature, condensate is drained by line 16, to the tar receptacle 17 In the cooler 1-5, the gas is brought to a temperature of about to F., at which temperature practically all the tar and Water originally contained in the gas is condensed. The condensate is brought from the cooler 15, by line 18, to the tar receptacle 17, as is also all tarry or aqueous condensate from the vxhauster '14, and the final tar extractor 19. The gas passes, actuated byexhauster 14,- through the final tar extractor 19, to the saturator 20, to be treated, as hereinafter described. The temperature of the gas leav-.

ing the cooler 15, at 75 to 85 F. is changed unavoidably in the exhauster by compression to about 100 F.

' The accumulated condensate in the receptacle 17, consists of tar, tarry oils and' ivater,-the latter containing a certain percentage of free and fixeiammoma, tlns 'Watenor Weak ammonia liquor, is brought to a separ'ting tank 21, here the tar sinks by gravity, thus. separating from the ammoniacal liquor. The tar is removed by the downwardly directed line 22, While the ammoniacal liquorfiows off from the top by line 23. either to a storageor feedtank, or, as shown in the diagram, directly into the still 2%. U p to this stage of the process no claims are made as to any improvements or tems in operation.

The ammonia still '24 is fed by the ammoniacal vapors through the top, the ammouiacal vapors being changed in temperature,

as hereinafter described. Almost any still for the manufacture of ammonia. vapors from \vea k ammoniacal iiqudr will answer the purpose. On top of still there is a. heat exchanger 25, wherein the aqueous vapors developed in the still and ascending, flowcoimter-current to the cold liquor'entering and. the vapors are thus cooled ofi to a tem- 'erature required by the pressure demanded by the seal 26, in the saturator hereinafter described. This cooling has a two-fold purpose: To make use of the sensible heat of the ammonia vapors, if beyond the requirements of pressure to heat the ammoniacal liquor, in order to economize steam in the stills, and secondly, to prevent hightemperature from carrying along in suspension a large amount of Water which may dilute the bath in the saturator. Furthermore the temperature of the ammoniacal vapors is thus regulated to produce the required heat energy to keep the bath, as Well as the gas in the saturator at agiven uniform temperature. The ammonia-cal vapors are conducted by means of pressure produced by their own initial or regulated temperature, through line 27, to saturator 20. Through cracker pipe 28, the vapors are brought into the acid bath, maintained at a separate level from that of the bath for the gas. The dip of the cracker pipe 28 into the bath is only as much, as the Wash or surge of the gas bath demands and is lessthan the-dip of the cracker pipe for gas, referred-to later on. The sulfate formed falls to the bottom of the satura-tor, While the Waste vapors ascendregular gas, contaminate the same as Well as reduce its heating power. Counter-current to the ascending Waste Vapors, sulfuric acid is sprayed in order to thoroughly wasn the vapors of the least traces of ammonia. This spray forms the acid feed for the central part of the, satura'tor bath, serving the high level of the total bath.

In order to catch particles of acid solution which may rise with the vapors, an acid spraycatcher 31, is inserted between the outlet of the secondary shell 29, and the Waste gas pipe *30, leading to the stack or atmosphere. The risidues of this catcher are collected in a mother liquor pit, not shown, and brought back to the saturator by means of a jet. .The secondary shell- 29 acts not only as a separator for vapors and gas, to prevent their mixing together by dipping into the acid'bath below/the level of the vapor and gas'cracker pipe, but it transfers the sensitive heat of the ascending waste vapors to the descending gas in the primary shell 32. Due to the high temperature of the ammoniacal vapors reaching the bath in the center of the saturator, aided by the temperature due to reaction of the sulfuric acid bath, the temperature of the bath inclosed .by the secondary shell 29, is much same bath two different temperatures, pro

duced entirely by waste heat of the product's treated. The separate level of the Vapor bath is estt'iblished by the fact that the waste vapors incased by the secondary shell :29, are subject to draft, as previously referred to, or if desired, to atmospheric pressure, the level of the gas bath being maintained by an atmospherical seal and level. regulator on the outside of the saturator shell.

The gas reaches the saturator 20, under pressure, through the primary shell 32, and takes up heat distributed by the secondary shell 29, as previously referred to. The temperature of the leaving the el'thausters at 100 is thus maintained, and the loss by radiation in the piping between the en hauster 14, and saturator 20, is balanced. The heating of the gas to a temperature permitting the absorption of the surplus water entering with the acid is therefore accomplished entirely in the bath, which received the heat energies required from the waste heat of the vapor bath, and the reaction of the acid in the total'bath. This temperature must be regulated as previously re" 'ferred to, the temperature of the heat depending entirely on the strength oi? the acid used in the process, hence it is necessary to remove, by means of the heat of the gas which is leaving the bath, all of the water which has been carried into the acid bath by incoming gas. No concise data can be given for the correct temperature to be maintained in the leaving, as this depends entirely and solely on the difference of vapor tension between water and the moisture of the bath. The regulation is accomplished by the temperature at which the ammoniacal vapors are permitted to leave the heat exchanger at the ammonia still; that is by the application and regulation of waste heat. From the primary shell 32, the gas is distributed by the cracker pipe 34, over the entiresurface of the saturator bath proper, and escapes under pressure by line 85, tothe acid spray separator 36, from whence it is distributed to the place of consumption. The gas leaving on the outside of the primary shell 32, under pressure will naturally depress the level ot the bath which, under atmospheric conditions, would be ec ual to that inside of the secondary shell 29. A balance is maintained by an molar seal and leyel regulator placed outside of the saturator and connected with the bath by a series of by-passes. The fluctuations in thebath on'the high pressure side of the saturator are thus controlled and an over-flow, is provided 111 the annular seal to maintain the high level of the bath inside the secondary shell.

The sulfate deposited by the entire bath, the hot and cold sections thereof, is removed by the ejector 33, to a series of drain,- tanks 37, from which the separated acid liquor is conducted to the annular seal and there usedv again in the saturator. This liquor retains a large amount of its original heat, and 1n my process thls heat is utilized in the annular seal to prevent radlation of heat from the top of the acid bath through the saturator walls.

I claim 1. The method of purifying gases. of carbonization which consists in separating from the gas the first condensate consistin of tars, tar oils and moisture,"decanting 0% the weak ammonia liquor, cooling the gas to F. in the saturator, then passing the gas to the distributing mains and the waste gases from the vapors to the atmosphere, substan tially as described.

2. The method of purifying gases of carbonization which consists in separating from the gas the first condensate consisting of tars. tar oils and moisture, decanting off the weak ammonia liquor, cooling the gas to a temperature oi 75 to F., distilling the resulting condensate and the weak ammonia liquor, compressing the gas to a point at which the temperature of the gas is approximately 100 1 then passing the gas through one compartment of a saturator andq'iassing the vapors of distillation of the ammonia liquor through a separate compartment of the same saturator, supplying said saturator with sulfuric acid by spraydug said acid into the departing 'apors. the

I sulfate from gases monia liberated from the coal by distillation, distilling-the condensate. and cooling the resultant vapors to a temperature consistent with the pressure of the seal required for the vapor bath in thesaturator this temperature to be of sufli cient degree to keep a portion of the vapor bath at its proper temperature, and toheat the bath for the gas inside the same saturator to a temperature notless than 105951, substane tially as described.

4. The method'of recovering ammonium sulfate from gases of carbonization, which comprises cooling of the'gases to free them from tarry matters, condensing the water vapors containing a certain percentage ammonia liberated from the coal by distillation, distilling the condensate and cooling the resultant vapors to a predetermined temperature, passing these vapors through a high temperature zone of the saturator and spraying sulfuric acid counter-current tothe Waste bath, substantially as described.

5. The method of recovering ammonium comprises cooling of the gases to free them from tarr'yomatters and Water vapors and condensing the Water vapors containing a certain percentage ofthe free and fixed an1- monia, liberated from the Coal by distillapors of and Water vapors, and

ofthe free and fixed vapors emerging from the acid of carbonization which tion, distilling the condensate and introducing' the gases of carbonization and the vadistillation independently into the saturator under differential pressure and at differential temperature, utilizing the higher heats of the vapors to keep a balance of temperature in the gas'entering the saturator simultaneously with the vapors and diffusing the high temperature of the vapor bath to maintain a proper low temperature in the bath for the gas, substantially as described. 4 g V v 6. The method of recoveringammonium sulfate from gases of carbonization, Which comprises cooling 'of the from tarrymat-ters'and Water-vapors and condensing the Water vapors containing a certain percentage of'thefree and fixed ammonia liberated from the coal by distillation, leading the gases'and vapors independently into the same saturator, removing the sulfate formed from the said saturator, draining the salts, extracted and' utilizing thejhot liquor-separated from the salts to prevent radiation of the bath through the outside Wallsof the saturator, substantially" as described. v

FREDERICK TSCHUDY.-

0011125 of this patent, may he obtained :01- five cents each, by addressing the F Commissioner of Patents,

Washington, D. C.

gases to free them- 

